The invention concerns a power tool wherein the tool is driven by a drive motor be means of a belt. The belt is guided about a drive pulley and an output pulley. A tensioning device is provided for the belt with which the spacing between the drive pulley and the output pulley can be changed, wherein the tensioning device has at least one tensioning position and at least one release position. The drive pulley and the output pulley in the tensioning position have a first spacing relative to one another and in the release position have a second smaller spacing.
U.S. Pat. No. 4,977,708 discloses a power tool with a two-part extension arm. A tensioning device acts between the two sections of the extension arm and, by means of a pressure spring, is secured in its end positions, i.e., an inoperative position and an operative position.